The invention relates to a method of recovering a highly purified vWF or a factor VIII/vWF-complex, respectively, from a biological starting material by means of immunoaffinity chromatography, as well as to a stable preparation containing highly purified vWF or factor VIII/vWF-complex.
Blood coagulation is a complex process including the sequential interaction of a series of components, in particular of fibrinogen, factor II, factor V, factor VII, factor VIII, factor IX, factor X, factor XI and factor XII. The loss of one of these components or the inhibition of its functionality causes an increased tendency of blood coagulation which may be life-threatening in some patients.
Von Willebrand factor (vWF) circulates in plasma complexed with factor VIII, factor VIII aiding blood coagulation and vWF in the complex with factor VIII stabilising the latter and protecting it from proteolytic degradation. On account of its function in the platelet aggregation, vWF also directly interferes in blood coagulation. vWF exists in plasma in a series of multimer forms of a molecular weight of from 1xc3x97106 to 20xc3x97106 Dalton. vWF is a glycoprotein primarily formed in the endothelial cells of mammals and subsequently liberated into circulation. In this connection, starting from a polypeptide chain having a molecular weight of approximately 220 kD, a vWF dimer having a molecular weight of 550 kD is formed in the cells by the formation of several sulfur bonds. Thereupon, further polymers of the vWF with ever increasing molecular weights, up to 20 million Dalton, are formed from the vWF dimers by linking. It is presumed that particularly the high-molecular vWF multimers have an essential importance in blood coagulation.
In hemophilia, blood coagulation is disturbed by a deficiency of certain plasmatic blood coagulation factors. In hemophilia A, the bleeding inclination is caused by a deficiency of factor VIII or a deficiency of vWF, respectively, which constitutes an essential component of factor VIII. Treatment of hemophilia A is effected primarily by substituting the lacking coagulation factor with factor concentrates, e.g. by infusion of factor VIII, factor VIII-complex or vWF.
vWF syndrome has several clinical pictures caused by an underproduction or an overproduction of vWF. Thus, an overproduction of vWF causes an increased thrombosis tendency. An undersupply caused by the absence or reduction of high-molecular forms of vWF is manifested in an increased bleeding tendency and an increased bleeding time on account of the inhibition of platelet aggregation and of wound closure.
A vWF deficiency may also cause a phenotypic hemophilia A, since vWF is an essential component of functional factor VIII. In these instances, the half-life of factor VIII is reduced to such an extent that its function in the blood coagulation cascade is impaired. Patients suffering from von Willebrand syndrome (vWD) thus frequently exhibit a factor VIII deficiency. In these patients, the reduced factor VIII activity is not the consequence of a defect of the X chromosomal gene, but an indirect consequence of the quantitative and qualitative change of vWF in plasma. The differentiation between hemophilia A and vWD may normally be effected by measuring the vWF antigen or by determining the ristocetin-cofactor activity. Both the vWF antigen content and the ristocetin cofactor activity are lowered in most vWD patients, whereas they are normal in hemophilia A patients.
Conventional methods for a therapy of von Willebrand syndrome use vWF recovered from plasma, and there are a number of attempts to treat vWD patients with purified vWF or factor VIII/vWF-complex. The development of monoclonal and polyclonal antibodies to blood factors, in particular to vWF, has enabled an improved isolation and purification of vWF or of factor VIII/vWF-complex from plasma or other biological sources.
Purification of factor VIII and of factor VIII/vWF-complex, respectively, from plasma is particularly rendered difficult by the fact that factor VIII occurs only in very small amounts in plasma, is extremely labile, and that the association of factor VIII with vWF is reversible under specific conditions.
By expressing factor VIII in recombinant cells (Wood et al., Nature 312: 330-337, 1984), it has been possible to prepare factor VIII by genetic engineering, yet it was only by the addition of or coexpression with vWF that a commercially usable yield of recombinant factor VIII could be achieved. Likewise, vWF has been prepared by genetical engineering methods and expressed in recombinant cells (Fischer et al., 1994, FEBS Letters 351: 345-348).
The recovery of purified factor VIII, vWF or factor VIII/vWF-complex from plasma or of factor VIII or vWF, respectively, from recombinant cells by means of various purification methods has also been described.
Zimmerman et al. (U.S. Pat. No. 4,361,509) describe a method of purifying factor VIII, wherein factor VIII/vWF complex is bound to a monoclonal anti-vWF antibody, and factor VIII is dissociated from the complex by means of CaCl2 ions. The thus obtained factor VIII subsequently is recovered in pure state via a further chromatographic step. The immunoaffinity carrier to which vWF is still adsorbed is regenerated by means of a chaotropic agent, in particular NaSCN, a vWF/NaSCN solution being incurred as a by-product and being discarded.
U.S. Pat. No. 5,006,642 describes the recovery of vWF from a solution that comprises vWF and a chaotropic agent and is incurred as a by-product according to U.S. Pat. No. 4,361,509, by dialysis against a suitable buffer or by desalting the solution in a further chromatographic step.
EP 0 383 234 describes the preparation of a vWF concentrate by means of anion exchange chromatography, wherein a factor VIII/vWF-complex contained in a solution is dissociated by the addition of a calcium- and amino acid-containing buffer, and a vWF concentrate is recovered.
EP 0 469 985 describes a method of preparing vWF from plasma cryoprecipitate, which is largely free from factor VIII, in which vWF is separated from factor VIII in a first purification step, wherein factor VIII binds to an anion exchanger, whereas vWF is not bound. In a second step, the salt concentration of the vWF-containing eluate is reduced, whereby vWF can bind to a second anion exchanger. Thereafter vWF is eluted by increasing the ionic strength.
A purified vWF which optionally is complexed with factor VIII is desirable for use in the therapy of patients afflicted with von Willebrand syndrome, but also of patients suffering from phenotypic hemophilia A. Furthermore, due to the stabilizing effect of vWF, a better storage stability of factor VIII preparations is attained.
To purify factor VIII/vWF-complex, it has been suggested to precipitate contaminating proteins, such as, e.g., fibrinogen, by means of high concentrations of amino acids, in particular glycine (WO 82/04395, EP 0 383 234).
EP 0 600 480 describes the purification of factor VIII/vWF-complex from plasma by means of a combination of anion/cation exchange chromatography, wherein the factor VIII/vWF-complex is stabilized with heparin and optionally lysine is added as an antiprotease.
EP 0 295 645 describes the purification of factor VIII/vWF-complex on an affinity matrix, wherein specific peptides binding to vWF are used as the affinity carrier, the complex binding to these peptides and subsequently being eluted with a pH gradient.
WO 96/10584 describes a method of recovering highly-purified recombinant vWF by means of a combined anion exchange/heparin-affinity chromatography, and EP 0 705 846 describes the separation between high- and low-molecular fractions of vWF.
Mejan et al. (1988, Thromb. Haemost. 59: 364-371) have suggested to purify factor VIII/vWF-complex from plasma by means of immunoaffinity. By using a vWF-specific antibody coupled to a carrier, factor VIII/vWF-complex is bound to the carrier under physiological conditions, and the complex is elated under alkaline conditions at a pH of 10.2. To neutralize the alkaline environment, the eluate is immediately admixed with 2 M of acetic acid, stabilized with human serum albumin and subsequently lyophilized. The weakly alkaline elution environment was particularly chosen so as to prevent a dissociation of factor VIII/vWF-complex and an inactivation of factor VIII.
However, it has been emphasized repeatedly that a particular difficulty in purifying the complex consists in maintaining the association of the proteins, since the complex of the two components is unstable. With their method, Mejan et al. (1988, Thromb. Haemost. 59: 364-371) achieved a 50% recovery of the factor VIII/vWF complex with a specific activity of factor VIIIxe2x89xa720 U/mg and vWFxe2x89xa720 U/mg. Under the elution conditions described, however, a partial liberation of the antibodies from the column has been observed, leading to a contamination of the eluate with approximately 90 ng/ml eluate on murine IgG. The antibodies thus had to be removed by a further chromatographic step.
Hornsey et al. (1987, Thromb. Haemost. 57: 102-105) examined the influence of different eluting agents in the immunoaffinity purification of factor VIII/vWF-complex and found that chaotropic agents, such as potassium iodide and lithium diiodosalicylates are particularly effective as eluting agents. The eluting agent used furthermore contained calcium chloride/ions as well as 1 M lysine for stabilizing the factor VIII and vWF activities. It has been observed that the high concentration of the amino acid protects the proteins from the denaturing effect of the chaotropic agent. Under the elution conditions used it was found that the final product was contaminated with the immunoadsorbent, here mouse monoclonal vWF antibodies, up to 30 ng/ml (approximately 300 ng/mg protein). On account of its high toxicity, the chaotropic desorption agent also had to be removed from the product by means of an additional purification step. By means of the immunoaffinity chromatography, Hornsey et al. (1987, Thromb. Haemost. 57: 102-105) obtained a yield of 57% factor VIII:C and 44% vWF, and a specific activity of 45 U of factor VIII and 60 U of ristocetin activity/mg protein.
Although the immunoaffinity is one of the preferred methods for the purification of vWF or of factor VIII/vWF-complex, the greatest disadvantage in the use of the immunoaffinity chromatography is the possible contamination of the final product with the immunoadsorbent, as well as the necessary regeneration of the affinity matrix used. The strong binding between antibody and vWFor factor VIII/vWF complex, respectively, frequently makes it necessary to use a strong desorption agent, such as, e.g., a chaotropic agent. By this, not only the activity and the molecular structure of vWF or of the factor VIII/vWF-complex are impaired, but due to a continuous liberation of antibodies from the carrier it also leads to a leakage of the immunocarrier. The half-life of the affinity carrier is strongly reduced, and its multiple usability is impaired. Since particularly for the commercial preparation of vWF or factor VIII/vWF-complex the use of immunoaffinity columns is very expensive, it would thus be desirable to provide a method which does not have these disadvantages.
It is thus the object of the present invention to provide an improved method of recovering vWF or factor VIII/vWF-complex by means of immunoaffinity chromatography, which does not have the disadvantages described above.
According to the invention, this object is achieved in that a method is provided in which vWF or a factor VIII/vWF-complex is purified by means of immunoaffinity chromatography, wherein a vWF or a factor VIII/vWF-complex bound to an immunoadsorbent is eluted by means of an eluting agent containing a zwitterion as a substantial active component.
As the zwitterions in the eluting agent, according to the present invention e.g. amino acids or analogues of amino acids can be used, whose isoelectric range lies between 3.2 and 9.6, and which are present as zwitterions in the neutral pH range. Therein, the preferred zwitterions are selected from the group of neutral amino acids or analogues of amito acids, preferably alanine, xcex2-alanine, 2-amino-butyrid acid, 4-amino-butyric acid, asparagine, citrulline, glutamine, glycine, histidine, isoleucine, leucine, methionine, phenylalanine, proline, sarcosine, serine, taurine, threonine, tryptophane and tyrosine, or betaines or analogues thereof, in particular sulfobetaines.
Particularly preferred for carrying out the method are the amino acids alanine, xcex2-alanine, glycine, histidine, phenylalanine or betaine. According to the present method, the zwitterions may be present in an aqueous solution at a concentration of between 0.01 and 0.5 M, preferably between 0.08 and0.2 M, particularly preferred between 0.1 and 0.15 M. There, aqueous solutions may be solutions which exclusively consist of water and do not contain any further additives.
According to the present method, the eluting agent containing the zwitterion may have a physiological pH, preferably a pH of between 6.5 and 8.0, especially preferred between 7.0 and 7.8, particularly preferred of 7.4. In this pH range, all the above-mentioned amino acids or analogues thereof are electrically neutral and present as zwitterions.
The eluting agent may be prepared by simply dissolving the amino acid or the analogue of an amino acid with the desired molarity in water. Since the pH and the ionic strength do not change or change only unsubstantially due to the neutral charge of the zwitterion, an adjustment of a pH or of the ionic strength is not necessarily required. Since in some instances an additonal stabilization of the eluate containing the vWF or the vWF-complex is desirable, e.g. if one or several virus inactivation steps are carried out, as further substances optionally sugar, such as sucrose, or maltose, can be added as stabilizers. Since these sugars also are chemically/physically neutral, an additon thereof does not change the pH of the eluting agent.
The use of amino acids, such as, e.g., glycine, histidine, or arginine as a precipitating agent, antiprotease or stabilizer or for an improved reconstitution of factor VIII solutions has,e.g., been described in EP 0 383 234 or in EP 0 600 480, the concentration of the amino acids used lying between 0.5-3 M. Moreover, amino acids have been known as a component of eluting agents or buffers in chromatographic methods. Tsang et al. (1991, J. Immunol. Methods 138: 291-299) have examined various dissociation conditions of antigens bound to immunoaffinity matrices and have found chaotropic agents to be the most effective dissociation reagents for breaking up antigen-antibody bonds. However, the specific activity of the eluted proteins was low on account of the denaturing effect of the chaotropic agents. The use of 0.5 M glycine, pH 2.0, as eluting reagent exhibited a comparatively low dissociation capacity and a relatively low specific activity of the protein recovered. The low pH of the eluting agent furthermore made it necessary to neutralize the eluate rapidly so as to avoid a further loss of activity of the protein. Likewise it has been found that antibodies detach from the carrier under these conditions and get into the eluate.
On account of what has been observed by Tsang et al. (1991, J. Immunol. Methods 138: 291-299) it has thus been the more surprising that it has been found within the scope of the present invention that an eluting agent containing a zwitterion as an essential active eluting reagent is capable of effectively dissociating an antibody/antigen complex under mild conditions and in the neutral pH range and without the use of chaotropic agents. On account of the mild elution conditions, the desired antigen is not only efficiently obtained in purified form and, on account of the high specificity to the antibody, free from contaminating components, but it can also be recovered substantially free from immunoadsorbent, since a dissociation of the antibody-antigen-complex does occur, yet the binding of the antibody to the carrier is not affected, and the antibody remains in stable association with the carrier.
To carry out the method according to the invention, as the ligand, any immunoadsorbent having a binding specificity to vWF, and capable of being immobilized on a solid carrier as ligand, may be used.
According to one embodiment of the method of the invention, an anti-vWF-antibody is used as the immunoadsorbent. The antibody used may be polyclonal or monoclonal. Monoclonal antibodies are, however, particularly preferred. To carry out the method according to the invention, all the known anti-vWF-antibodies may be used, e.g. such as have been described by Goodall et al. (Thromb. Haemost. 54: 878-891, 1985). Preferably, a monoclonal vWF antibody from a hybridoma, selected from the series of cell hybridisations of murine myeloma X63 and splenocytes of BALB/C mouse, immunized with factor VIII/vWF-complex, as, e.g., described in EP 0 179 006, is used.
According to a preferred embodiment, as the ligand for carrying out the method of the invention, a fragment of an anti-vWF-antibody that binds vWF or factor VIII/vWF-complex, respectively, is used. Particularly preferred is the Fxe2x80x2ab-fragment of a vWF antibody. Using a fragment of a specific antibody has the advantage that an affinity carrier matrix with the antibody fragment as the ligand can be prepared in a simple manner, whereby, due to the small molecular size of the ligand, the antigen binding capacity and the binding efficiency of the carrier can be increased. Also the risk of a contamination of the product by a complete antibody possibly getting into the eluate is greatly reduced and thus negligible.
The immunoadsorbent preferably is immobilized on a carrier, wherein all the known natural or synthetic insoluble polymers suitable for affinity chromatography can be used as the carrier.
The method according to the invention constitutes a simple and efficient method of recovering vWF or factor VIII/vWF-complex having a high specific activity and in a high yield from an optionally not pre-purified protein solution. Any biological solution, e.g. plasma, a plasma pool, a plasma fraction, a cryoprecipitate, the supernatant of a cell culture expressing recombinant vWF or factor VIII or co-expressing factor VIII and vWF, respectively, or a pre-purified protein solution may be used as the starting material containing vWF or a factor VIII/vWF-complex. The present invention is, however, particularly suitable for recovering vWF or factor VIII/vWF-complex from non-pre-purified protein solutions, e.g. directly from plasma or from the supernatant of a recombinant cell culture. According to the present invention, vWF or factor VIII/vWF-complex contained in a starting material is bound to the immunoadsorbent, preferably under physiological conditions. There, the starting solution is adjusted to a pH of between 6.5 and 7.8, at a temperature of between 4xc2x0 C. and 20xc2x0 C., and is contacted with the immunoadsorbent, whereby, on account of the specific binding capacity of the antibody to vWF, vWF or factor VIII complexed with vWF, respectively, is bound, whereas other proteins contained in the solution are not bound and thus are separated in a simple manner from vWF or from factor VIII/vWF-complex.
By means of the method according to the invention and elution with a buffer in the neutral pH range, containing a zwitterion as an essential eluting agent, vWF or factor VIII/vWF-complex can be recovered from the immunoadsorbent with a particularly high efficiency. On account of the specific interaction of vWF and factor VIII in a complex, also factor VIII complexed with vWF is bound, whereas free, non-complexed factor VIII cannot bind to the immunoadsorbent. By aid of the method according to the invention, thus a pure vWF or factor VIII complexed exclusively with vWF, respectively, is recovered. It has particularly been found that approximately 85% of the vWF or of the factor VIII/vWF-complex present in the starting material can be recovered. Thus, by means of the method according to the invention, vWF or factor VIII/vWF complex, respectively, is recovered in a purity of more than 90%, preferably of more than 95%. This high recovery rate and purity has not been attained by means of the hitherto described chromatographic methods in one method step. Moreover, the use of the eluting agent described and the mild eluting conditions have the advantage that the association of factor VIII with vWF, and thus the physiological and molecular structure of the complex, are retained.
The method according to the invention has the further particular advantage that before and during the elution, a change of the pH of the solution containing the proteins is not necessary and the biological activity of the protein to be purified is not impaired by a change of the pH.
By using the above-described eluting agents, the vWF or the vWF-complex, respectively, is efficiently desorbed from the immunoadsorbent, without impairing the structural integrity of the vWF and the activities of the vWF or factor VIII. The intactness of the structural integrity of vWF was particularly proved by vWF multimer analysis, as, e.g., described in EP 0 705 846, before adsorption and after elution from the immunocarrier. Likewise it has been shown that the collagen binding activity as well as the specific platelet agglutination activity of the vWF substantially is not impaired.
A comparison of the factor VIII:Ag to the factor VIII:C-activity in the starting material and after elution from the carrier showed that the ratio does not change. The specific activity preferably is  greater than 80 U/mg.
The highly purified vWF or factor VIII/vWF-complex obtained with the method according to the invention may likewise be further purified by chromatographic methods known from the prior art, such as ion exchange, affinity or gel filtration chromatography. Purified factor VIII/vWF-complex may, e.g., be adsorbed to an affinity carrier that, specifically binds either vWF or factor VIII, and the proteins may be recovered separately from each other and in free form by means of a buffer which dissociates the complex, e.g. a buffer having a low pH, a high ionic strength, and containing CaCl2 or NaCl. With this procedure it is possible to selectively recover free factor VIII which is not complexed with vWF, or vWF not complexed with factor VIII, respectively. The thus isolated proteins or antigens are particularly characterized by not being impaired in terms of their vWF binding or their factor VIII binding, respectively. By this it is possible to purposefully recover highly purified factor VIII having a high vWF binding specificity, or highly purified vWF having a high factor VIII binding specificity, respectively, in relationship to the antigen content.
The present invention thus also comprises highly purified vWF having a factor VIII-binding capacity of more than 90%, preferably more than 95%, and factor VIII having a vWF binding affinity of at least 90%, respectively. A thus purified vWF or factor VIII/vWF-complex, respectively, may be further purified by means of heparin affinity chromatography, e.g. as described in EP 0 705 846, whereby high-molecular vWF multimers are enriched. The thus obtained vWF or factor VIII/vWF complex, respectively, particularly comprising high-molecular vWF multimers is characterized by a high specific platelet aggregation of at least 60 U/mg protein.
By the method according to the invention, in particular purified vWF or factor VIII/vWF-complex, respectively, is recovered in an aqueous solution containing a zwitterion at a concentration of between 0.08 M and 0.2 M, and at a pH of between 7.3 and 7.8, the zwitterion being selected from the group of the amino acids glycine, alanine, xcex2-alanine, phenylalanine, and histidine, or of the betaines. This purified vWF or factor VIII/vWF-complex then may optionally be subjected to a further virus depletion and/or virus inactivation step known from the prior art.
The purified solution may, e.g. be directly sterile-filtered via-a filter having a pore width of between 100 nM and 0.45 xcexcm, and lyophilized without the addition of a stabilizer, in particular a high-molecular stabilizer.
The method according to the invention may be used for purifying and recovering recombinant or plasmatic vWF or factor VIII/vWF-complex, respectively.
A further object of the present invention relates to a stable preparation containing highly purified vWF or factor VIII/vWF-complex obtainable by immunoaffinity chromatography. According to the present invention, the stable preparation contains vWF having a purity of at least 95%, and a specific antigen-activity of at least 95 U/mg protein, preferably of 100 U/mg protein. A stable preparation provided according to the invention and containing factor VIII/vWF complex has a purity of at least 95%, preferably of 99%, the specific activity of factor VIII:C being at least 95 U/mg protein and that of vWF being at least 95 U/mg protein, the ratio of the specific activity in the complex thus being 1:1.
According to a particular embodiment, the factor VIII/vWF-complex consists of recombinant factor VIII and recombinant vWF, the ratio of factor VIII to vWF being between 0.01 and 100, preferably between 1:30 and 1:70, particularly preferred at approximately 1:50. Within the scope of the invention it has been found that the cell culture supernatants of recombinant vWF- or factor VIII-expressing cells having a defined concentration of antigen can be mixed in a certain, desired ratio, and that after having carried out the method of the invention, purified complex consisting of recombinant proteins can also be recovered again in the desired ratio.
It has been known that during its purification from plasma or from cryoprecipitate, vWF is degraded into low-molecular vWF fragments by proteases possibly present, which fragments then can be identified in SDS gel as low-molecular fraction having satellite bands (Furlan et al., 1993, PNAS. 90: 7503-7507). Furthermore, factor VIII is partly activated by proteases present, whereby the specific activity of the factor VIII/vWF-complex is reduced.
According to a further aspect of the present invention, a stable preparation comprising highly purified vWF or factor VIII/vWF-complex, respectively, is provided, which is particularly characterized in that the molecular and structural integrity of the vWF or of the factor VIII/vWF-complex, respectively, is substantially retained and that it does not contain any proteolytic degradation products of the vWF or activated factor VIII.
According to a further aspect, the preparation according to the invention is substantially free from impurities caused by the immunoadsorbent, the amount of possibly present immunoadsorbent, in particular of antibodies, being less than 15 ng/mg protein, preferably less than 10 ng/mg protein, and particularly preferred less than 7 ng/mg protein. Moreover, the preparation according to the invention is characterized in that it contains less than 3%, preferably less than 1%, fibrinogen and less than 1%, preferably less than 0.5%, fibronectin. The determination of the fibrinogen and fibronectin contents, respectively, there was effected by means of ELISA in accordance with the prior art.
Within the scope of the present invention it has also been shown that particularly by using an eluting agent containing as the essential eluting agent in the buffer an amino acid, such as glycine, histidine or alanine, which hitherto have also been used for stabilizing protein solutions, the eluted vWF or factor VIII/vWF-complex can be kept in a stabilizing environment during the entire purification procedure and thus the preparation obtained is particularly stable.
The preparation according to the invention is stable in solution for a period of at least 2 weeks at 4xc2x0 C., deep-frozen at xe2x88x9220xc2x0 C. for at least 6 months, and as a lyophilisate for at least 1 year at a temeprature of from xe2x88x9220xc2x0 C. to 4xc2x0 C. By the presence of, e.g., histidine in the eluting agent, furthermore a precipitation of the vWF or factor VIII/vWF-complex, respectively, at lyophilization is prevented. The preparation according to the invention thus may optionally be further processed to a lyophilized product without any further additives. To improve the reconstitution of the lyophilized preparation, arginine may also be admixed, as has been described, e.g., in WO 93/22336. The stable preparation may be formulated for administration to man in a respective manner as a stable pharmaceutical preparation and may contain suitable buffers or physiologically acceptable carriers. As has already been mentioned above, on account of its particularly good stability of the preparation, the addition of a stabilizer optionally can be omitted. It has been known that by the addition of a stabilizer, in particular of HSA, the specific activity of an antigen preparation is reduced, whereby the pharmaceutical composition to be administered has a lower specific activity than the protein preparation recovered directly after purification.
According to the present invention, thus a pharmaceutical composition containing vWF or factor VIII/vWF-complex having a purity of at least 95%, preferably 99%, and a specific activity of vWF of at least 95 U/mg and of factor VIII of at least 95 U/mg is provided which is substantially free-from high-molecular substances and stabilizers, in particular free from HSA. By this, the pharmaceutical preparation according to the invention differs from any hitherto known pharmaceutical compositions which contain substances, such as albumin or heparin, for stabilization thereof.
In principle, no further complex re-formulation of the purified preparation is required for its administration to man, since the purified product can already be recovered from the affinity carrier in a physiologically compatible composition. Likewise, it is already present in the eluate in a stable and stabilized form.
The method according to the invention thus constitutes a simple method for the gentle recovery of highly purified vWF or factor VIII/vWF-complex, respectively, and for the simple production of a stable pharmaceutical preparation, which optionally may be used directly for a therapeutical application.
Before processing the highly purified vWF or vWF-complex, respectively, to a pharmaceutical preparation it is advantageous to carry out an inactivation or depletion of viruses. This may be effected by a chemical and/or physical treatment known in the prior art. Since due to the presence of amino acids, such as glycine, alanine or histidine, contained in the stable preparation according to the invention, vWF or factor VIII/vWF complex is present in a physiological and stabilizing environment, the purified product may, optionally without any further addition of stabilizers, be directly subjected to a virus inactivation step.
The stable preparation provided according to the present invention may be used for producing a medicament for the treatment of hemophilia A or vWD.